One technique for switching, by means of software, radio networks to be a connection destination is software defined radio. In the following, the software defined radio is referred to as software defined radio, and a radio device making use of the software defined radio is referred to as a software defined radio device.
The software defined radio is a technique to make the corresponding radio device cope with various radio communication systems by only changing the software operated on that radio device. The software defined radio has such an advantageous effect of enabling a single radio device to connect to various radio networks without changing the hardware. As follows, software operating on this software defined radio device and defining the radio communication method is referred to as waveform software. To which radio communication method, a software defined radio device corresponds is determined in accordance with the content described in the waveform software.
The following patent literatures describe exemplary systems switching the radio communication methods, i.e., switching radio networks, by applying the software defined radio.
In handover (switch) between communication areas of different communication methods from each other, in the system described in PTL 1, a base station radio device that corresponds to a first communication method receives, from a mobile station radio device, a signal representing a radio quality of a signal received from the base station radio device, and downloads waveform software of a second communication method in the mobile station radio device according to a first condition of the received signal representing the radio quality. Then, the base station radio device corresponding to the first communication method handovers the mobile station radio device to the base station radio device which corresponds to the second communication method according to a second condition of the radio quality.
In PTL 2, the radio communication terminal that can switch the plurality of radio communication methods by means of software defined radio monitors, for each radio communication method, the carrier interference and noise power ratio: CINR, received signal strength indictor: RSSI, the state of the consumption power of the radio apparatus and the like, and based on the QoS (quality of service) required in communication and the monitoring result, determines the priority order of the plurality of radio communication methods. The radio communication method to be used, i.e., the waveform software to be used, is changed according to this priority order.
The communication system described in PTL 3 is such that, in a radio communication system constituted by a plurality of software defined radio devices and an update server storing therein a waveform application, each software defined radio device selects and executes an executable component from among the waveform software components downloaded from the update server, based on the profile representing its hardware specification.
The software defined radio terminal described in PTL 4, when being changed to a specific communication method using a reconfigurable radio circuit, calculates the temperature value of the reconfigurable radio circuit as state information, transmits, to a terminal management apparatus, the specific communication method identification information, its own terminal identification information, and the state information, as setting parameter detection condition, receives a setting parameter matching the setting parameter detection condition from the terminal management apparatus and sets the setting parameter to each circuit, and switches the communication methods, i.e., changes the waveform software to be used.
The multi-link communication apparatus described in PTL 5 determines the number of available radio communication systems and radio links based on the base station information, the service requirement conditions, and the terminal information, and performs multi-link communication with the multi-link terminal via the base station.